Method and apparatus for predicting the orbit and detecting the type of a satellite

Abstract

A method of predicting the orbit of a satellite of a satellite positioning system, including: associating first and second types of satellites with first and second models of celestial mechanics forces, respectively; storing first ephemerides data of a satellite, associated to first time intervals and second ephemerides data associated to second time intervals. Further, the method comprises: calculating reference satellite positions based on the first ephemerides data; estimating first and second satellite positions in the first time intervals by using the second ephemerides data and the first and second forces models, respectively; determining first and second estimate errors by comparing the reference positions with the first and second positions, respectively; and detecting the type of satellite between the first and second types by an analysis of the first and second errors.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the priority benefit of Italian Patent Application No. MI2013A001424, filed Aug. 29, 2013, and which application is hereby incorporated by reference to the maximum extent allowable by law.BACKGROUND[0002]1. Technical Field[0003]The present disclosure refers to the satellite positioning systems, and particularly refers to the prediction of satellite orbits.[0004]2. Discussion of the Related Art[0005]As is known, a GNSS (Global Navigation Satellite System) receiver, for example a GPS (Global Positioning System), for calculating its position, receives correctly formatted electromagnetic signals transmitted by a constellation of satellites orbiting around earth. The receiver position is determined by a triangulation process which requires a rather complex procedure.[0006]Initially, the GPS receiver, by a process known as acquisition, needs to locate a sufficient number of satellites and “hook” to them. However, the GPS...

AI Technical Summary

Benefits of technology

The patent text describes a method and apparatus for predicting the orbit of a satellite in a satellite positioning system. The method involves using models of celestial mechanics forces to predict the satellite's position based on ephemerides data and solar radiation pressure. The method can detect the type of satellite by analyzing the errors between the predicted position and the actual position. The technical effect of this patent is to improve the accuracy of satellite positioning by accounting for the errors caused by the solar radiation pressure model and the shape and size of the satellite.

Problems solved by technology

If the reception of this data is interrupted, for example due to a building or tree, the receiver needs to wait additional time to download the missing data from the satellite.

In real conditions, wherein the GPS receiver is often in motion, some minutes are required for the receiver to obtain the availability of all the needed data for making its calculations and obtaining the “fix”, this fact causes an extreme uncertainty about the position before the navigation starts.

It is observed that the information regarding the type of a satellite is not a datum transmitted by the satellite itself and therefore cannot be available to the receiver.

If the orbit of a satellite is predicted in dependence of a solar radiation pressure model referred to another type of satellite, such prediction is affected by an error influencing the position calculation of the receiving apparatus and therefore the fix calculation.

The Applicant observes that the prediction of the satellites orbits performed according to the known techniques can be affected by errors due to the fact that such prediction is performed by considering a celestial mechanics model which, specifically referring to the action of the solar radiation pressure, is not suitable to the actually used satellite.

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